1. Technical Field
The present invention relates to a chronograph timepiece, and more specifically to a, chronograph timepiece which is driven and controlled electrically and electronically and is suitable to be reset to zero mechanically. Also, in this specification, “the chronograph timepiece” refers to a timepiece having a chronograph function.
2. Related Art
In a type of chronograph timepiece which is mechanically driven and controlled and further mechanically reset to zero, there is one having a reset-to-zero mechanism where a position of a hammer lever itself is adjusted by a guide pin and is displaced such that three hammers are arranged with respect to corresponding heart cams (a self-alignment is performed), and the three hammers of the hammer lever cause the corresponding heart cams to be reset to zero (JP-A-2004-294277)
However, in the chronograph timepiece disclosed in JP-A-2004-294277, the reset-to-zero mechanism requires an operating cam provided with two kinds of gears such as a ratchet gear and a driving gear so as to perform each of start, stop, and reset actions, and further requires a plurality of levers or spring members related to each action so as to perform each via the operating cam. Thus, a number of components are necessary, thereby the structure is complex, the assemblability is poor, which leads to high costs.
In a type of a chronograph timepiece which is driven and controlled electrically and electronically, and is reset to zero mechanically, there has been proposed one in which a position or a displacement of a hammer lever having a plurality of hammers is controlled by a plurality of levers and spring members, without using the operating cam (for example, Japanese Utility Model Registration No. 2605696 or JP-A-2004-264036).
The reset-to-zero mechanism in Japanese Utility Model Registration No. 2605696 includes a hammer lever (the term in Japanese Utility Model Registration No. 2605696 is a “hammer operating lever”) having a plurality of hammers, a first lever that can be engaged with a reset button in a rear anchor portion of a rear anchor side arm portion and has a forward end side arm portion with an interposed rotation center, and a second lever that is engaged with the forward end portion of the forward end side arm portion of the first lever in the rear anchor portion of the rear anchor side arm portion which is engaged with the hammer lever in the forward end of the forward end side arm portion and which is positioned at the rear anchor side of the rotation center and that can be engaged with a start/stop button in the vicinity of the rear anchor portion. Thereby, it has the minimal number of the levers.
However, in the reset-to-zero mechanism in Japanese Utility Model Registration No. 2605696, the first and second levers can perform only an action such as see-sawing, and thus, for example, when the start/stop button is pressed during the chronograph time measurement action and then a stopping action is performed, the start/stop button is not engaged with the second lever but just electrically connected to a switch contact point, thereby performing the stop action. Therefore, a user cannot reliably obtain a sense where the start/stop button is reliably pressed, it is easy to generate a defective operating or a defective instruction, and further the usability is poor.
On the other hand, in the reset-to-zero mechanism in JP-A-2004-264036, if the pressing action is completed using the start/stop button or the reset button a start-stop lever (the term in JP-A-2004-264036 is an “operating lever”) or a hammer instruction lever group (the term in JP-A-2004-264036 is an “operating lever” and a “hammer operating lever”) which have been displaced by the start/stop button or the reset button can return to original positions, and the sense of the start/stop button or the reset button being pushed down can be obtained when the start-stop lever or the hammer instruction lever is made to move to change positions from the original positions to the displaced positions. More specifically, in the reset-to-zero mechanism in JP-A-2004-264036, after the pressing of start/stop button or the reset button is completed, in order to cause the start-stop lever or the hammer instruction lever to return to the original position, the start-stop lever which is directly rotated by pressing the start/stop button, or the forward end side lever of the hammer instruction lever group which is directly rotated by pressing the reset button is fitted to and engaged with the hammer lever having a plurality of hammers with allowance, and thus the start-stop lever or the hammer instruction lever can return to the original position regardless of the position of the hammer lever.
However, in the case of the reset-to-zero mechanism of JP-A-2004-264036, since the start-stop lever or the hammer instruction lever (hammer operating lever) is fitted to and engaged with the hammer lever with allowance, it is difficult to prevent directions of a force applied to the hammer lever from being complicated, and a position of the hammer lever itself is adjusted and displaced. Therefore, it is difficult to employ the structure (the self-alignment structure) where the three hammers of the hammer lever cause the corresponding heart cams to be reset to zero.
In addition, in the reset-to-zero structure in JP-A-2004-264036, two levers (the terms in JP-A-2004-264036 are an “operating lever” and a “hammer operating lever”) are necessary as the hammer instruction lever group, and they each respectively rotate around the separate rotation centers, and thus a taken-up region capable of performing the rotation of the lever increases.
Further, in a type of a chronograph timepiece where a hammer of a hammer lever moves roughly linearly and strikes a heart cam for the reset-to-zero, there is a problem in that when the hammer applies the reset-to-zero force to a tip of the heart cam towards a rotation center of the heart cam, it is difficult for the heart cam to be reset to zero.
In a chronograph timepiece where a hammer causes a heart cam to be reset to zero, if the hammer causes the heart cam to suddenly rotate, there is a concern that a display indication hand main body portion (a feather-shaped portion) and an installment portion (a skirt-shaped tube portion which is attached by being fitted to the chronograph stem) of a chronograph indication hand installed in a chronograph stem in which the heart cam is positioned is damaged. This concern is heightened as the chronograph indication hand becomes thinner and longer.